bc1a85977b
BPF tail call uses the BPF_MAP_TYPE_PROG_ARRAY type map for calling
into other BPF programs and this PROG_ARRAY should be filled prior to
use. Currently, samples with the PROG_ARRAY type MAP fill this program
array with bpf_load. For bpf_load to fill this map, kernel BPF program
must specify the section with specific format of <prog_type>/<array_idx>
(e.g. SEC("socket/0"))
But by using libbpf instead of bpf_load, user program can specify which
programs should be added to PROG_ARRAY. The advantage of this approach
is that you can selectively add only the programs you want, rather than
adding all of them to PROG_ARRAY, and it's much more intuitive than the
traditional approach.
This commit refactors user programs with the PROG_ARRAY type MAP with
libbpf instead of using bpf_load.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200516040608.1377876-4-danieltimlee@gmail.com
107 lines
2.5 KiB
C
107 lines
2.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <stdio.h>
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#include <assert.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include "sock_example.h"
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#include <unistd.h>
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#include <arpa/inet.h>
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#include <sys/resource.h>
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struct flow_key_record {
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__be32 src;
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__be32 dst;
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union {
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__be32 ports;
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__be16 port16[2];
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};
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__u32 ip_proto;
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};
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struct pair {
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__u64 packets;
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__u64 bytes;
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};
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int main(int argc, char **argv)
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{
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int i, sock, key, fd, main_prog_fd, jmp_table_fd, hash_map_fd;
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struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
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struct bpf_program *prog;
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struct bpf_object *obj;
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char filename[256];
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const char *title;
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FILE *f;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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setrlimit(RLIMIT_MEMLOCK, &r);
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obj = bpf_object__open_file(filename, NULL);
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if (libbpf_get_error(obj)) {
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fprintf(stderr, "ERROR: opening BPF object file failed\n");
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return 0;
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}
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/* load BPF program */
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if (bpf_object__load(obj)) {
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fprintf(stderr, "ERROR: loading BPF object file failed\n");
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goto cleanup;
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}
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jmp_table_fd = bpf_object__find_map_fd_by_name(obj, "jmp_table");
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hash_map_fd = bpf_object__find_map_fd_by_name(obj, "hash_map");
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if (jmp_table_fd < 0 || hash_map_fd < 0) {
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fprintf(stderr, "ERROR: finding a map in obj file failed\n");
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goto cleanup;
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}
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bpf_object__for_each_program(prog, obj) {
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fd = bpf_program__fd(prog);
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title = bpf_program__title(prog, false);
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if (sscanf(title, "socket/%d", &key) != 1) {
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fprintf(stderr, "ERROR: finding prog failed\n");
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goto cleanup;
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}
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if (key == 0)
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main_prog_fd = fd;
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else
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bpf_map_update_elem(jmp_table_fd, &key, &fd, BPF_ANY);
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}
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sock = open_raw_sock("lo");
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/* attach BPF program to socket */
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assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &main_prog_fd,
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sizeof(__u32)) == 0);
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if (argc > 1)
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f = popen("ping -4 -c5 localhost", "r");
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else
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f = popen("netperf -l 4 localhost", "r");
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(void) f;
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for (i = 0; i < 5; i++) {
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struct flow_key_record key = {}, next_key;
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struct pair value;
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sleep(1);
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printf("IP src.port -> dst.port bytes packets\n");
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while (bpf_map_get_next_key(hash_map_fd, &key, &next_key) == 0) {
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bpf_map_lookup_elem(hash_map_fd, &next_key, &value);
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printf("%s.%05d -> %s.%05d %12lld %12lld\n",
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inet_ntoa((struct in_addr){htonl(next_key.src)}),
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next_key.port16[0],
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inet_ntoa((struct in_addr){htonl(next_key.dst)}),
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next_key.port16[1],
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value.bytes, value.packets);
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key = next_key;
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}
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}
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cleanup:
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bpf_object__close(obj);
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return 0;
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}
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